The proposed research will examine the cholinergic involvement in ethanol-induced modifications of photic evoked cortical macropotentials in rats. Acetylcholine systems will be manipulated via i.p. injections of physostigmine salicylate (0.3 mg./kg.) and atropine sulfate (5.0 mg./kg.). Examination of the effects of these drugs, given both alone and in combination with ethanol (2.0 g./kg.), should provide an indication of the extent to which alcohol-induced modifications of cortical evoked potentials in rats are mediated by cholinergic mechanisms. Given a similarity between the effects of alcohol on photic evoked potentials in both humans and rats, the results provided by this study may ultimately lead to useful treatments for the human chronic alcoholic.